Scatter/primary in mammography: Comprehensive results

Abstract

Monte Carlo procedures using the SIERRA code (validated in a companion article) were used to investigate the scatter properties in mammography. The scatter to primary ratio (SPR) was used for quantifying scatter levels as a function of beam spectrum, position in the field, air gap, breast thickness, tissue composition, and the area of the field of view (FOV). The geometry of slot scan mammography was also simulated, and SPR values were calculated as a function of slot width. The influence of large air gaps (to 30 cm) was also studied in the context of magnification mammography. X-ray energy and tissue composition from 100% adipose to 100% glandular demonstrated little effect on the SPR. Air gaps over a range from 0 to 30 mm showed only slight effects. The SPR increased with increased breast thickness and with larger fields of view. Measurements from 82 mammograms provided estimates of the range of compressed breast thickness (median: 5.2 cm, 95% range: 2.4 cm to 7.9 cm) and projected breast area onto the film (left craniocaudal view, median: 146 cm2, 95% range: 58 cm2 to 298 cm2). SPR values for semicircular breast shapes, Mo/Mo spectra, and a 15 mm air gap were parametrized as a function of breast thickness and (semicircular) breast diameter. With the coefficients a = - 2.35452817439093, b = 22.3960980055927, and c = 8.85064260299289, the equation SPR= [a + b x (diameter in cm)--(-1.5) + c x (thickness in cm) --(-0.5)]-- -1 produces SPR data from 2 to 8 cm and from 3 to 30 cm breast diameters with an average error of about 1%.

Clinical Digital Breast Tomosynthesis System: Dosimetric Characterization

“…Furthermore, for the breast phantom representing the "average" breast (5.0 cm thick, 50% glandular fraction) (23,24), the MGDs for the FFDM and DBT acquisitions were 1.20 and 1.30 mGy, respectively, resulting in a difference of only 8% between the two modalities, and a fusion two-dimensional-threedimensional imaging study resulted in an MGD of 2.50 mGy. Hendrick et al Note.-Data are total tube current-exposure time products (in milliampere seconds) for all 15 projections.…”

Evaluation of scattered radiation in mammography examination with Si detector

“…Some of the X-ray photons from generated low energy spectra are scattered when they interact with a target material. According to the results published by different authors [23,24] the scattered radiation in mammography contributes to the total registered radiation with 40−80%. Backscattering directions of approximately 180 • and 90 • dominate for low energy photons.…”

Modelling of low energy X-ray scattering in radiation detectors with protective coatings

“…Some attempt to compare the experimental and Monte Carlo modelling results concerning low energy photon scattering effects in Si detectors and to evaluate the influence of scattering processes on the absorbed total dose to patient has been made in our previous work [8]. Previous results on Monte Carlo simulation of low energy X-ray photon scattering effects in different materials are presented in [9,10]. However, the existing information is not sufficient for understanding the discrepancies that occur between experimental and modelling data.…”